This Invention relates to a broad band digital and/or analog high-power broadcast antenna for signals. A dual-adjacent channel television antenna is disclosed.
A high-power U.H.F. television broadcast transmitting station requires and includes complete transmitting facilities, as well as an antenna that is mounted atop a tall supporting structure. The antenna is responsible for directing the transmitted signals that carry the television pictures and sound and/or other signals to an audience. It is the job of the antenna to focus the signals toward the audience. In order to operate properly, the antenna must precisely match the required electrical conditions that attend a particular frequency associated with the operating channel(s). For example television channels are assigned by the Federal Communications Commission in the U.S., and by similar governmental agencies in other countries throughout the world. Traditionally, each television antenna is designed and built to operate over a single channel that is 6.0 MHz wide. Once the antenna is built, that operating frequency is fixed and cannot practically be changes. As the country and the world changes from analog to digital technology, and as existing television channel frequencies are re-assigned to other services, most television stations will be required to change both the mode of operation, i.e. from analog to digital transmission, and to be assigned new operating channels in the U.H.F. television frequency band. In many cases, through either an interim channel assignment and/or a requirement for simultaneous digital and analog television broadcasts, there is a requirement for the broadcast of multiple television channels from the same transmitting site at the same time. Many of these channel assignments are adjacent to one another. This fact then generates a need for a high power antenna that can be used to transmit the channels simultaneously, while at the same time, providing the required electrical parameters to the television transmitting equipment over channels. For example, this would require an antenna that will operate over 12.0 MHz of the television broadcast band for two channels and not the 6.0 MHz band for a single channel. With appropriate television transmitter combining equipment, a single antenna and transmission line may be used to simultaneously transmit the two adjacent channels at the same transmitting site. This invention covers the engineering and design of the high-power transmitting antenna that has both the electrical bandwidth to simultaneously accommodate up to two adjacent 6.0 MHz television channels, while at the same time, providing the appropriate power tolerance and antenna gain to implement the antenna system for up to two full-power television channels. This antenna invention will accommodate two digital channels, two analog-channels or one digital and one analog channel.
Virtually every television broadcast station in the United States, and then in most other countries throughout the world must convert from the older analog television broadcast mode to the new, high definition digital television broadcast mode. Most of these television stations will have to change their operating frequency, as well as switch from the analog to the new digital mode. This transition process is expected to be completed over a number of years. In many cases, the transition process will involve the broadcast of the new high-definition digital television signals, while at the same time, broadcasting the older analog television signals on a U.H.F. adjacent channel. This simulcast period will be necessary in order to allow time for the viewing audience acquire the necessary digital television sets. This simulcast process will require the use of two separate television channels, each occupying six megahertz of frequency bandwidth. Traditionally, television stations would install a transmitting antenna designed to handle the single 6.0 MHz channel assigned to that particular station. In addition, some television stations desire to share broadcasting facilities in order to reduce the cost of the required transition. In either case, most antenna systems in place now for the single stations are designed to operate on a single assigned channel.
This particular invention covers a new, simple, cost effective implementation of a full, high-power U.H.F. television broadcast antenna system that is fully capable of handling two adjacent 6.0 MHz television channels simultaneously.
It is an object of this invention to increase the efficiency of usage of each antenna transmitting facility;
It is another object of this invention to reduce the complexity of the antenna systems for television broadcast stations;
It is another object of this invention to provide a television broadcast antenna system that will transmit two adjacent television channels simultaneously using the same antenna and transmission line;
It is another object of this invention to reduce the number of antenna systems that are required for the number of operating television channels;
It is another object of this invention to allow two separate television broadcasters to share a common antenna system;
It is another object of this invention to provide increased frequency bandwidth for single-channel stations.
It is another object of this invention to provide V.S.W.R. profiles that are nearly flat over the entire 12 MHz, two-channel operating band, in order to ensure high integrity transmission of digital signals;
Other objects and a more complete understanding of the invention may be had by referring to the following drawings in which: